Fluid injection systems, such as sprayers, suffer from a number of drawbacks. First, current systems fail to accurately inject product at the desired rate and concentration. For instance, some systems require continuous dilution of the product within the container prior to spraying. As such, the concentration of product being dispensed decreases over time. These and other systems are also unable to inject small, continuous quantities of product into the feeder fluid so as to produce a diluted product at low concentration. Instead, such systems periodically inject discrete aliquots of product into the fluid stream. Alternative systems divert a portion of the feeder fluid from the fluid path and use this portion to push product out of the container and into the fluid stream. However, such systems require multiple components making adjusting the feed rate and resultant dilution difficult and time consuming.
Thus, there remains a need for a fluid injection system and device including a venturi tube with an adjustable valve stem that operates to change the pressure differential across the venturi tube to allow for an adjustable, settable pressure differential for selectively setting the desired feed rate of the product within a dilution type feeder device. The present invention satisfies these, as well as other, needs.